Ethers Raman frequencies

Indium(III) iodide is a yellow hygroscopic crystalline solid, mp 210°. The compound exists in the solid state as iodine bridged dimers (I2lnl2lnl2) and is readily soluble in organic solvents such as benzene, chloroform, and diethyl ether. The vibrational spectrum has been reported, but the observed infrared and Raman frequencies occur in the far-infrared region, below 250 cm . ... 

The direct evidence on which our view of cation solvation in polymer electrolytes is based comes mainly from spectroscopic techniques. IR and Raman studies have been carried out on a variety of systems (see Chapter 5, Torell and Schantz, 1989 and Freeh, Manning, Teeters and Black, 1988). Low frequency vibrational modes, around 860-870 cm associated with the cation-ether oxygen interactions in PEG based systems have been observed they are absent in PEO itself... 

The Raman spectra of arsenious chloride,2 in the liquid and gaseous states, of light and heavy arsine3 and of sodium arsenite and sodium arsenate,4 have been examined and frequencies obtained. The Raman spectra of the chloride and bromide in solution in ether or benzene consist of the spectra of the pure solute and pure solvent only, indicating that chemical combination does not occur in the solution.6 With solutions in methyl and ethyl alcohols, the frequencies of the latter are unchanged, but those of arsenious chloride are lowered somewhat.6... 

The analysis of the same compounds, in the liquid state, at 300 K did not reveal enough differences to suggest a change in their structure. The spectra of the samples in the solid state (90 K) have a better resolution, which is due to the crystalline correlation effect and the decrease in temperature. The similarity of the frequencies observed for the Mg—X stretching vibration bands in the Raman spectra (Table 2) of the liquids and solids confirm the similarities of the structures. In the liquid state, the diethyl ether molecules are still in the GG conformation. 

Hyponitrous acid. In contrast to nitrous and nitric acids, hyponitrous acid crystallizes from ether as colourless crystals which easily decompose, explosively if heated. The detailed molecular structure of this acid has not been determined, but it is known that the molecular weights of the free acid and its esters correspond to the double formula, H2N2O2, that it is decomposed by sulphuric acid to N2O, and that it can be reduced to hydrazine, H2N-NH2. Infrared and Raman studies show conclusively that the hyponitrite ion has the trans configuration (a), but the N-N frequency suggests that the central bond has an order of rather less than two. ... 

Of importance in connection with the solubility of the metals in liquid ammonia are ammonia solvates such as the [Na(NH3)4]+ ion which is formed on treatment of Nal with liquid ammonia. [Na(NH3)4]I is a liquid of fair thermal stability. It freezes at 3° and at 25° has an equilibrium pressure of NH3 of 420 mm thus it must be kept in an atmosphere of ammonia with at least this pressure at 25°. The infrared and Raman spectra indicate the complex ion [Na(NH3)4]+ to be tetrahedral with Na—N bonds about as strong as the Zn—N bonds in [Zn(NH3)4]2+ or the Pb—C bonds in Pb(CH3)4. Bending and rocking frequencies, however, are quite low, suggesting that the Na—N bonding is mainly due to ion-dipole forces. Thus it may be assumed that Na+ and other metal ions in the dilute liquid ammonia, amine and ether solutions are strongly solvated in the same way. 

Comerford et- al. C533 combined infrared spectra and Raman spectra Best results were achieved by concatenating the data from both sources and treating them as a single vector. Predictive abilities for esters, alcohols, ethers, compounds containing C=C double bonds and ketones ranged from 89 to 100 % (mean 95 %). The decision vectors have been used for the assignment of vibrational frequencies. 

Polyphenylene oxide, or polyphenylene ether, is an amorphous polymer for which the IR and Raman spectra are presented in Reference Spectrum 45. As expected from the chemical structure, bands relevant to the aromatic ring system are observed at 1601, 1492, and 858 cm (IR), and 1603 and 835 cm (Raman)—the low-frequency band in the IR being associated with the substitution of the aromatic ring. The other important feature of the IR spectrum of polyphenylene oxide is the intense absorption band at 1188 cm associated with the ether bonding. 

These spectra were plotted from runs on a Jarrell-Ash 25-300 Raman spectrophotometer with a 4880 A argon ion laser. In some spectra the region from 4000 to 2000 cm" has been plotted so that the intensity is 0.5 times its true value compared to the rest of the spectrum. These are marked xO.5. Like the infrared spectra, these Raman spectra illustrate a group frequencies which are labeled directly on the spectra. Groups illustrated include alkanes in spectra 1-6, cyclohexanes 7-8, aromatics 9-12,15,17,18,20,21,25, 32-34, double bonds 13,14,24, isocyanate 15, triple bond 16, nitrile 17,18, carbonyls 19-26, alcohols 27-29, ether 30, amines 31, 32, nitro 33, C—Cl 34, C Br 35, and mercaptan 36. A molecular formula index of the Raman spectra follows. 

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